Interesting question. Silver Stars fly under the radar here, despite having decades of production. I never would have heard of them had not a pack been included in a sampler I bought early on. I find them to be very sharp, close to Feathers, but perhaps slightly less so. SS is one of my favorite blades for sharpness and smoothness.
I use SS regularly, and get three excellent shaves per blade. I could stretch that to four, but it takes extra passes to get the shave I want. On the other hand, I only get two excellent shaves per Feather blade, with a third day requiring extra passes. For me, SS hold their edge better than Feathers.
Silver star compared to Feather blades